This invention relates to a radio pager receiver that can receive a message signal carrying messages and destined to the pager receiver.
A recent technical development has brought about a radio pager receiver which can provide not only an indication of a call received by the pager receiver but also visual display of messages on a display unit. Such a radio pager receiver comprises a memory having a message area for storing the messages. A memory capacity of the memory tends to increase to satisfy a recent demand.
The messages stored in the message area are erased by disconnection of main electric power from a power supply circuit comprising a main battery. The disconnection occurs, for example, when the power supply circuit is deenergized by a switch to carry out exchange of the main battery.
In order to prevent such erasure of the messages stored in the memory, a memory backup method is generally used wherein the memory is backed up by backup electric power from a backup power source. The backup power source is, for example, a backup battery, a capacitor of a large capacitance for accumulating the main electric power. When the power supply circuit is deenergized by the switch, the backup power source delivers the backup electric power to the memory.
In Japanese Unexamined Utility Model Prepublication or Kokai No. Syo 60-59650, namely, 59650/1985, a conventional radio pager receiver of the type described is disclosed by the present applicants and one other person. The conventional pager receiver is also disclosed in U.S. patent application Ser. No. 655,287 filed Sept. 28, 1984 by Toshihiro Mori et al for assignment to the instant assignee, European Patent Application No. 84111639.5, Canadian Patent Application No. 464,273 and Australian Patent Application No. 33616/1984.
In the conventional radio pager receiver, a memory has a file administration information area for storing file administration information in addition to the message storing area. The file administration information is for use in administrating the messages stored in the message area. Specifically, the file administration information comprises file information indicative of storage addresses of the messages stored in the message area and reception order information indicative of reception order of the messages stored in the message area. The memory is backed up by backup electric power from a backup power source when a power supply circuit is deenergized by a switch in the manner described above.
It is to be noted here that the messages and the file administration information are not always correctly kept in the memory when the power supply circuit is again energized after once deenergized. The memory backup may not be correctly executed, for example, when the backup power of the backup power source has been reduced. However, the conventional radio pager receiver is incapable of informing whether or not the memory backup is correctly executed. This is because the pager receiver is incapable of judging whether or not the messages and the file administration information are correctly kept in the memory when the power supply circuit is again energized. Such judgement cannot be made with reference to only the file administration information which is related to the messages and which is stored in the memory.
Likewise, the conventional pager receiver is incapable of judging whether or not each of the messages stored in the memory is subjected to a backup operation by the backup electric power when the power supply circuit is energized. In other words, it is impossible to judge whether or not the each of the messages stored in the memory is newly received and stored in the memory without being subjected to the backup operation. It is therefore impossible to display the each of the messages stored in the memory together with an announcement indicating whether or not the each of the messages is subjected to the backup operation.